Rifle-sight



33-254. cm 1.935997% S. I. PRESCOTT.

RIFLE SIGHT.

l APPLICATION FILED FEB. 21, I919. 1,359,740. Patented Nov. 23, 1920.

UNITED SYDNEY I. PRESCOTT, OF NEW YORK, N. Y.

RIFLE-SIGHT.

Specification of Letters Patent.

Patented Nov. 23, 1920.

Application filed February 21, 1919. Serial No. 278,366.

270613, and the invention relates to an improvement in rifle sights.

When an object to be hit is a long but unknown distance away, even an experienced rifleman has considerable difliculty in correctly estimating the range and aiming his rifle to make an accurate shot. Objects seem nearer when in a bright light, when their color contrasts with the color of the background, when viewed over water, snow, or an even surface, or from a higher point, and in the clear atmosphere of high altitudes; and they seem more distant when viewed over a valley, or from a lower point, in a fog or poor light, or when only a small part of the object is visible. But even if the range is correctly estimated, it does not follow that good holding and smooth trigger pulling will result in a hit even with an accurate rifle and in a calm. There are other disturbing influences which may singly or in combination affect the aim. For example, a rifle is said to shoot low when it is dirty, or hot, on a cold day, or a cloudy day, when the target is dull, when shooting in the sun, or when the wind blows from the target to the rifleman; and is said to shoot high when it is clean, or cold, on a hot day, or a moist day, when the target is in the sun, or when the wind blows from the rifleman to the target. In some instances one or more of these dis turbing influences may be offset by others; in other instances, they may be augmented thereby. The best sights heretofore produced are provided with devices for accurately adjusting them so that the angle of elevation may be changed in definite degree when necessary. These devices, usually graduated for half-minutes or minutes of elevation angle have the effect of moving the point of impact on a target different distances with different rifles because the sighting radii of different rifles vary. In such sights, the elevation of the sight member is effected by means of a single-thread screw which must be rotated many times in order to give the sight member the proper elevation for long ranges. When using one, the rifleman must carry data showing its effect for the particular rifle and ammunition with which it is used, and consult it before ad- JUStlDg his sights either for range or for correct on of elevation. This takes time and time 1s important when the object aimed at is moving game or another man shooting at the rifleman. The main object of the present lnventlon is the production of a rifle sight as accurate as the best sights heretofore known, but materially faster in operation. Another object is the production of a fast slght the operating mechanism of which is determined by the trajectory of the bullet used in the rifle to which it is attached, and graduated to graphically show what adjustment must be made for any desired range. another object is the production of such a sight provided with half-minute graduations whereby adjustment may be quickly corrected when the range has been incorrectly estimated or any other aim disturbing influence 1S effective. Still another object is to include in such a sight all of the differentranges sighted for within one rotation of the elevating member, thereby increasing speed of adjustment. And the final object is the production of a sight having the above mentioned advantages and yet simpler and more durable than any accurate sight heretofore known. The invention consists in certain constructions and combinations which will be hereinafter fully described and then specifically set forth in the claims hereunto appended.

In the accompanying drawings, which form a part of this specification and in which like characters of reference indicate the same or like parts, Figures 1, 2 and 3 are respectively plan, centralsectional elevation, and end elevation, of a device constructed in accordance with the invention.

In carrying the invention into effect, there is provided a sight member of any approved type, open or peep, and a rotatable elevating member having an operating surface which may be a cam surface of progressively increasing pitch or a threaded surface of uniform pitch and also having a scale indicating the various ranges sighted for, the pitch of said operating surface being determined by the trajectory of the bullet used, and the graduations of the scale being determined by the trajectory and by the character of the elevating surface; that is, uniform when a cam surface of progressively increasing pitch is used, or progressively increasing if a threaded surface of uniform pitch is used. In the best constructions, the elevating member is also provided with a scale independent of the range scale and determined by the pitch of the operating surface, the particular province of this scale being to justify or correct adjustments of the range scale when the latter is in inaccurate adjustment from any of the causes hereinbefore pointed out. In the best constructions also, the elevating member is a nut held against all lost motion or other movement, except the rotating movement necessary to cause the elevation of the sight member, by means of a supporting forked base between the jaws of which the nut is frictionally held, this base being provided with means for attachment to a rifle. All of the above mentioned members and means may be varied in construction within wide limits as expressed in the claims. The particular device selected to illustrate the invention is but one of many possible concrete embodiments of the same, and the invention therefore is not to be restricted to the details of the structure shown and herein described in detail. It may be here remarked that although the illustrative structure shown is designed for attachment to the firing pin of a bolt-action high-intensity rifle, a skilled mechanic can readily adapt it for attachment to the tang, to the receiver, or to the barrel of a rifle; and, if desired, add a wind gage of well known con struction.

Referring to the drawings, 4 indicates a sight member having a guiding section 5, a pair of guiding pins 6, 6, and an intermediate threaded section 7. The particular rifle for which the illustrative structure was designed is a high-intensity bolt-action rifle handling a powerful cartridge the bullet of which has an extremely fiat trajectory. It is accurate at long ranges. The sight was therefore designed for long ranges, and in order to make possible the elevation necessary for long ranges without sacrificing accuracy and in the shortest possible time, the intermediate threaded section 7 has a multiple thread; specifically, a quadruple 16 thread. This multiple thread has a lead of .250 which is more than sufiicient to elevate the sight member for 1000 yard range within one rotation of the elevating nut to be presently described. In a sight of this type designed for use with a rifle handling a cartridge the bullet of which has a higher trajectory, the pitch of the thread would have to be increased because a greater elevation would be necessary for equivalent ranges, or, sacrificing speed of operation, the elevating nut would have to be rotated more than once to adjust the sight member for the longer ranges. The pitch of the thread is thus determined by the trajectory of the bullet used. The sight member is provided with a peep aperture 8 of a well known type.

A nut 9 having a knurled slightly raised ring 10, by means of which it may be rotated, is provided with a corresponding multiple thread engaging the intermediate threaded section 7 of the sight member. It will be readily understood that rotation of the nut will produce rapid longitudinal movement of the sight member. The nut 8 is made a friction fit between the jaws 13 and 14 of the forked base in order to prevent lost motion and accidental displacement of the adjustment of the sight member, and the bearing surfaces are all large enough to eliminate appreciable wear during the ordinary life of a rifle.

For the purpose of supporting the sight member and elevating nut, there is provided a forked base 11 having a threaded stem 12 by means of which it is attached to the firing pin of a rifle, an upper jaw 13 having an aperture in which the guiding section 5 of the sight member is adapted to slide, and a lower jaw it having two apertures in which the guiding pins 6, 6 of the sight member are adapted to slide. The guiding section and guiding pins are accurately fitted in their respective apertures and the engagement of the pins with the lower aw apertures prevent rotation of the sight mcnr her during its movements. There is therefore no wabbling of the sight member wherever it may be adjusted.

For the purpose of graphically indicating to the rifleman just how much he must rotate the elevating nut to adjust the sight for any range sighted for, the upper jaw of the forked base is provided with a zero mark 15 and the upper edge of the nut is graduated in accordance with the trajectory of the bullet used, the graduations progressively increasing to compensate for the progressive falling movement of the bullet during its flight. The fixed sight range is 100 yards, the trajectory of the bullet being so fiat that no adjustment for shorter ranges is necessary, and in the drawings the nut is shown in fixed sight position. It is graduated for every 25 yards from the fixed sight range to and including 1000 yards, the proper elevation for the latter range being reached when the nut is rotated 330 degrees. The method of marking the various ranges. is clearly shown in this figure and no further description is deemed necessary.

For the purpose of graphically indicating to the rifleman just how much the nut should be rotated to justify or correct a poor estimate of the range, or to correct aiming error sTsiCsL zes tnw due to any of the disturbing influences hereinbefore mentioned, the lower jaw of the forked base is provided with a zero mark 16 in exact alinement with the range zero mark 15 before referred to, and the lower edge of the nut is graduated in half-minutes and minutes of elevation angle, the spacing of these graduations being uniform because the pitch of the thread is uniform and deter-- mined by the pitch of the thread because the elevation corresponding to one halfminute of elevation angle is .00415 and the amplitude of nut movement to produce this elevation depends upon the pitch of the thread. A change of one minute of elevation angle has the effect of moving the point of impact one inch at 100 yards, two inches at 200 yards, three inches at 300 yards, four inches at 400 yards, and so on. This is easily remembered, and it is the only data required.

No sight can compensate for human error in holding on the object aimed at, or for inherent rifle inaccuracies, but assuming that a rifleman has an accurate rifie equipped with this sight and holds true, sees a head of big game walk into the water across a bay, estimates its distance as 400 yards, with one motion whirls the sight nut to the mark 4:, he fires and sees the bullet strike the water in line but 20 inches too low. He knows that 20 inches too low at 400 yards means 5 minutes of elevation angle, so without removing his rifle from his shoulder he quickly advances the nut 5 minutes and makes a hit with the next shot. lVhether the aiming error was due to poor range guessing, or atmospheric conditions, or a combination of both, is unimportant because the total error was quickly and accurately corrected.

In view of the foregoing, it is thought that no further description of the operation of the device is necessary, and it is therefore omitted in the interest of brevity.

l/Vhat is claimed is:

1. In a rifle sight, the combination with a sight member, of a rotatable elevating member having an operating surface in movement controlling engagement with said sight member and also having two independent scales one indicating the various ranges sighted for and the other indicating angles of elevation, the pitch of said operating surface and the graduations of said range scale being determined by the trajectory of the bullet used and the graduations of said angle scale being determined by the pitch of said operating surface.

2. In a rifle sight, the combination with a threaded sight member, of an elevating nut engaging the thread of said sight member and having a scale indicating the various ranges sighted for, the pitch of said thread and the graduations of said scale being determined by the trajectory of the bullet used.

8. In a rifle sight, the combination with a threaded sight member, of an elevating nut engaging the thread of said sight member and having two independent scales one indicating the various ranges sighted for and the other indicating angles of elevation, the pitch of the thread and the graduations of the range scale being determined by the trajectory of the bullet used and the graduations of the angle scale being determined by the pitch of the thread.

t. In a rifle sight, the combination with a threaded sight member, of a supporting base therefor, an elevating nut engaging the thread of said sight member and having two independent scales. one indicating the various ranges sighted for and the other indicating angles of elevation, the pitch of the thread and the graduations of the range scale being determined by the trajectory of the bullet used and the graduations of the angle scale being determined by the pitch of the thread, and means in relative sliding engagement with said sight member and said base for preventing rotation of said sight member.

5. In a rifle sight, the combination with a sight member having a multiple thread, of an elevating nut having a corresponding multiple thread engaging the sight member thread, said thread being determined by the trajectory of the bullet used and adapted to cause the sight member to be elevated for the greatest range sighted for within one rotation of said nut.

6. In a rifle sight, the combination with a sight member having a multiple thread, of an elevating nut having a corresponding multiple thread engaging the sight member thread and also having a scale indicating the various ranges sighted for, the pitch of said thread and the graduations of said scale being determined by the trajectory of the bullet used.

7. In a rifle sight, the combination with a sight member having a multiple thread, of an elevating nut having a corresponding multiple thread engaging the sight member thread and also having two independent scales one indicating the various ranges sighted for and the other indicating angles of elevation, the pitch of said thread and the graduations of the range scale being determined by the trajectory of the bullet used and the graduations of the angle scale being determined by the pitch of the multiple thread.

In testimony whereof, I have signed my name to this specification.

SYDNEY I. PRESCOTT. 

